Water containing elevated levels of sodium is often unsuitable for useful applications, such as the irrigation of plants, the consumption by animals, and the consumption by humans. Such water can pose major environmental concerns. Discharging water having high sodium content into streams, rivers, ponds, wetlands and the like can have adverse impacts on the surrounding land, vegetation and animals. Because of these impacts, there are regulations in place setting forth the limits on the quality of water that may be discharged.
One source of water that is rich in sodium is the coal bed methane (CBM) industry, which produces billions of gallons of such water each year as a byproduct of the process of extracting methane gas. Coal bed methane gas is found in coal seams beneath the earth's surface. The extraction of this methane gas from the underground coal seams requires the pumping of large quantities of water in order to release the pressure that holds the methane gas within the coal seams. In this extracting process, when the water pressure around the coal seams is reduced, the methane detaches from the coal and flows to a recovery well. Once to the surface, the methane gas is directed to pipelines and the water is left as a byproduct that must be dealt with.
The amount of water produced by a single CBM well can vary greatly from as little as one gallon per minute up to 100 gallons per minute. One study estimates that the typical CBM well produces an average of 10 gallons of water per minute over the course of its life. At that rate, the typical well will produce an average of 14,400 gallons of water per day throughout its life.
The relatively high concentration of sodium in CBM water can affect crop growth. When the level of sodium is high compared to the levels of magnesium and calcium, it can degrade the physical and chemical properties of the soil. Sodium can cause soil crusting, thereby affecting water availability and aeration, and can lead to dispersion and migration of clay particles. All of these factors have a negative impact on plant growth. Water is considered “sodic” when it contains high levels of sodium. Sodicity of water can be expressed as the Sodium Adsorption Ratio (SAR). The SAR is the relative amount of sodium in water compared to the amounts of calcium and magnesium and can be expressed as:
  SAR  =            Na      +                                            Ca                          2              +                                +                      Mg                          2              +                                      2            The USDA defines water having an SAR greater than 12 as sodic. Additionally, CBM water can also contain methane gas, iron, and manganese.
Accordingly, a need exists for an apparatus and method that allow water rich in sodium to be treated through the removal of at least a portion of the sodium. A need also exists for an apparatus and method that can remove methane gas from water. A further need exists for an apparatus and method that can economically and safely reduce water's SAR by reducing its sodium levels.